Olfactory adaptation is a phenomenon that is generally understood to include a decrease in sensitivity to an odorant that results from exposure to that odorant. Such adaptation can result, at least in part, from peripheral events, such as fatigue of the receptor.
Cross-adaptation is a phenomenon that is generally understood to include a decrease in sensitivity to one odorant, e.g., odorant B, that results from exposure to a different odorant, e.g., odorant A. Cross-adaptation can result from competition for receptor sites in the periphery. For example, when odorant A occupies the receptors that would be preferentially occupied by odorant B, it may induce cross-adaptation in that receptor and desensitize the population of receptors to odorant B.
Alternatively, cross-adaptation can result from the processing of information about odors within brain circuitry. For example, if odorants A and B both utilize, at least in part, the same circuits, and the system is occupied by processing information about odorant A, then the individual will be less sensitive to odorant B because there is competing information being processed. If odorant B is an unpleasant or unwanted odor, for example, that of underarm sweat, also called axillary odor, and odorant A is a pleasant-smelling odorant or fragrance, then the presence of the pleasant-smelling odorant could act as a cross-adapting agent to diminish the impact of the axillary odor.
Body odors, including axillary odors, are produced by males and females. It is generally recognized that both sexes produce more axillary odors during times of stress and/or strong emotional situations. The apocrine glands are sensitive to blood levels of epinephrine (adrenaline). Stress and other strong emotional situations increase blood levels of adrenaline causing the apocrine glands to rapidly secrete relatively large amounts of their contents to the skin surface. Stress-derived axillary odor is produced during episodes of high apocrine gland output via rapid metabolism of apocrine gland-rich axillary secretions by cutaneous axillary bacteria.
Although it is often desirable to reduce the perception of malodors by both sexes, females are known to be more sensitive to a number of odorants including, but not limited to, axillary odorants and display, on average, greater olfactory sensitivity to odorants than males. In addition, females exhibit greater olfactory sensitivity to odorants at certain times in their menstrual cycle. It is desirable to identify methods and agents for reducing the perception of male and female body odors by women, as well as the perception of male and female body odors by men.
Agents that are capable of reducing the perception of body odors may be used in cosmetic and personal products, including, but not limited to, gender-specific cosmetics and personal products. They may also be used in compositions that reduce the perception of malodors, including gender-specific malodors. For example, it could be desirable to include cross-adapting agents in goods directed to females that selectively block or reduce male or female malodors. Similarly, it could be desirable to include fragrances in goods directed to males that selectively block or reduce male or female malodors. It could also be desirable to use such agents in compositions and methods that are not gender-specific.